1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*- */
2 /* This Source Code Form is subject to the terms of the Mozilla Public
3 * License, v. 2.0. If a copy of the MPL was not distributed with this
4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6 #ifndef StartupCache_h_
7 #define StartupCache_h_
9 #include "nsClassHashtable.h"
10 #include "nsComponentManagerUtils.h"
11 #include "nsZipArchive.h"
12 #include "nsIStartupCache.h"
14 #include "nsIMemoryReporter.h"
15 #include "nsIObserverService.h"
16 #include "nsIObserver.h"
17 #include "nsIOutputStream.h"
19 #include "mozilla/Attributes.h"
20 #include "mozilla/MemoryReporting.h"
21 #include "mozilla/StaticPtr.h"
24 * The StartupCache is a persistent cache of simple key-value pairs,
25 * where the keys are null-terminated c-strings and the values are
26 * arbitrary data, passed as a (char*, size) tuple.
28 * Clients should use the GetSingleton() static method to access the cache. It
29 * will be available from the end of XPCOM init (NS_InitXPCOM3 in nsXPComInit.cpp),
30 * until XPCOM shutdown begins. The GetSingleton() method will return null if the cache
31 * is unavailable. The cache is only provided for libxul builds --
32 * it will fail to link in non-libxul builds. The XPCOM interface is provided
33 * only to allow compiled-code tests; clients should avoid using it.
35 * The API provided is very simple: GetBuffer() returns a buffer that was previously
36 * stored in the cache (if any), and PutBuffer() inserts a buffer into the cache.
37 * GetBuffer returns a new buffer, and the caller must take ownership of it.
38 * PutBuffer will assert if the client attempts to insert a buffer with the same name as
39 * an existing entry. The cache makes a copy of the passed-in buffer, so client
42 * InvalidateCache() may be called if a client suspects data corruption
43 * or wishes to invalidate for any other reason. This will remove all existing cache data.
44 * Additionally, the static method IgnoreDiskCache() can be called if it is
45 * believed that the on-disk cache file is itself corrupt. This call implicitly
46 * calls InvalidateCache (if the singleton has been initialized) to ensure any
47 * data already read from disk is discarded. The cache will not load data from
48 * the disk file until a successful write occurs.
50 * Finally, getDebugObjectOutputStream() allows debug code to wrap an objectstream
51 * with a debug objectstream, to check for multiply-referenced objects. These will
52 * generally fail to deserialize correctly, unless they are stateless singletons or the
53 * client maintains their own object data map for deserialization.
55 * Writes before the final-ui-startup notification are placed in an intermediate
56 * cache in memory, then written out to disk at a later time, to get writes off the
57 * startup path. In any case, clients should not rely on being able to GetBuffer()
58 * data that is written to the cache, since it may not have been written to disk or
59 * another client may have invalidated the cache. In other words, it should be used as
60 * a cache only, and not a reliable persistent store.
62 * Some utility functions are provided in StartupCacheUtils. These functions wrap the
63 * buffers into object streams, which may be useful for serializing objects. Note
64 * the above caution about multiply-referenced objects, though -- the streams are just
65 * as 'dumb' as the underlying buffers about multiply-referenced objects. They just
66 * provide some convenience in writing out data.
75 nsAutoArrayPtr
<char> data
;
78 CacheEntry() : data(nullptr), size(0) { }
80 // Takes possession of buf
81 CacheEntry(char* buf
, uint32_t len
) : data(buf
), size(len
) { }
87 size_t SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf
) {
88 return mallocSizeOf(data
);
92 // We don't want to refcount StartupCache, and ObserverService wants to
93 // refcount its listeners, so we'll let it refcount this instead.
94 class StartupCacheListener MOZ_FINAL
: public nsIObserver
96 ~StartupCacheListener() {}
97 NS_DECL_THREADSAFE_ISUPPORTS
101 class StartupCache
: public nsIMemoryReporter
104 friend class StartupCacheListener
;
105 friend class StartupCacheWrapper
;
108 NS_DECL_THREADSAFE_ISUPPORTS
109 NS_DECL_NSIMEMORYREPORTER
111 // StartupCache methods. See above comments for a more detailed description.
113 // Returns a buffer that was previously stored, caller takes ownership.
114 nsresult
GetBuffer(const char* id
, char** outbuf
, uint32_t* length
);
116 // Stores a buffer. Caller keeps ownership, we make a copy.
117 nsresult
PutBuffer(const char* id
, const char* inbuf
, uint32_t length
);
119 // Removes the cache file.
120 void InvalidateCache();
122 // Signal that data should not be loaded from the cache file
123 static void IgnoreDiskCache();
125 // In DEBUG builds, returns a stream that will attempt to check for
126 // and disallow multiple writes of the same object.
127 nsresult
GetDebugObjectOutputStream(nsIObjectOutputStream
* aStream
,
128 nsIObjectOutputStream
** outStream
);
130 nsresult
RecordAgesAlways();
132 static StartupCache
* GetSingleton();
133 static void DeleteSingleton();
135 // This measures all the heap memory used by the StartupCache, i.e. it
136 // excludes the mapping.
137 size_t HeapSizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf
);
139 size_t SizeOfMapping();
143 virtual ~StartupCache();
145 enum TelemetrifyAge
{
149 static enum TelemetrifyAge gPostFlushAgeAction
;
151 nsresult
LoadArchive(enum TelemetrifyAge flag
);
154 nsresult
ResetStartupWriteTimer();
155 void WaitOnWriteThread();
157 static nsresult
InitSingleton();
158 static void WriteTimeout(nsITimer
*aTimer
, void *aClosure
);
159 static void ThreadedWrite(void *aClosure
);
161 static size_t SizeOfEntryExcludingThis(const nsACString
& key
,
162 const nsAutoPtr
<CacheEntry
>& data
,
163 mozilla::MallocSizeOf mallocSizeOf
,
166 nsClassHashtable
<nsCStringHashKey
, CacheEntry
> mTable
;
167 nsRefPtr
<nsZipArchive
> mArchive
;
168 nsCOMPtr
<nsIFile
> mFile
;
170 nsCOMPtr
<nsIObserverService
> mObserverService
;
171 nsRefPtr
<StartupCacheListener
> mListener
;
172 nsCOMPtr
<nsITimer
> mTimer
;
174 bool mStartupWriteInitiated
;
176 static StaticRefPtr
<StartupCache
> gStartupCache
;
177 static bool gShutdownInitiated
;
178 static bool gIgnoreDiskCache
;
179 PRThread
*mWriteThread
;
181 nsTHashtable
<nsISupportsHashKey
> mWriteObjectMap
;
185 // This debug outputstream attempts to detect if clients are writing multiple
186 // references to the same object. We only support that if that object
189 class StartupCacheDebugOutputStream MOZ_FINAL
190 : public nsIObjectOutputStream
192 ~StartupCacheDebugOutputStream() {}
195 NS_DECL_NSIOBJECTOUTPUTSTREAM
197 StartupCacheDebugOutputStream (nsIObjectOutputStream
* binaryStream
,
198 nsTHashtable
<nsISupportsHashKey
>* objectMap
)
199 : mBinaryStream(binaryStream
), mObjectMap(objectMap
) { }
201 NS_FORWARD_SAFE_NSIBINARYOUTPUTSTREAM(mBinaryStream
)
202 NS_FORWARD_SAFE_NSIOUTPUTSTREAM(mBinaryStream
)
204 bool CheckReferences(nsISupports
* aObject
);
206 nsCOMPtr
<nsIObjectOutputStream
> mBinaryStream
;
207 nsTHashtable
<nsISupportsHashKey
> *mObjectMap
;
211 // XPCOM wrapper interface provided for tests only.
212 #define NS_STARTUPCACHE_CID \
213 {0xae4505a9, 0x87ab, 0x477c, \
214 {0xb5, 0x77, 0xf9, 0x23, 0x57, 0xed, 0xa8, 0x84}}
215 // contract id: "@mozilla.org/startupcache/cache;1"
217 class StartupCacheWrapper MOZ_FINAL
218 : public nsIStartupCache
220 ~StartupCacheWrapper() {}
222 NS_DECL_THREADSAFE_ISUPPORTS
223 NS_DECL_NSISTARTUPCACHE
225 static StartupCacheWrapper
* GetSingleton();
226 static StartupCacheWrapper
*gStartupCacheWrapper
;
229 } // namespace scache
230 } // namespace mozilla
231 #endif //StartupCache_h_